The impact of an object on a granular solid is an ubiquitous phenomenon in nature, the scale of which ranges from the impact of a raindrop onto sand all the way to that of a large asteroid on a planet. Despite the obvious relevance of these impact events, the study of the underlying physics mechanisms that guide them is relatively young, with most work concentrated in the past decade. Upon impact, an object starts to interact with a granular bed and experiences a drag force from the sand. This ultimately leads to phenomena such as crater formation and the creation of a transient cavity that upon collapse may cause a jet to appear from above the surface of the sand. This review provides an overview of research that targets these phenomena, from the perspective of the analogous but markedly different impact of an object on a liquid. It successively addresses the drag an object experiences inside a granular bed, the expansion and collapse of the cavity created by the object leading to the formation of a jet, and the remarkable role played by the air that resides within the pores between the grains.

中文翻译：

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对颗粒床的影响

物体对粒状固体的撞击是自然界中普遍存在的现象，其规模从雨滴对沙子的撞击一直到行星上的大型小行星的撞击。尽管这些撞击事件具有明显的相关性，但对指导它们的潜在物理机制的研究相对年轻，大多数工作集中在过去十年。撞击后，物体开始与颗粒床相互作用，并受到沙子的拖曳力。这最终会导致诸如陨石坑形成和瞬态空洞的产生等现象，该空洞在坍塌时可能会导致从沙子表面上方出现射流。本综述从物体对液体的类似但明显不同的影响的角度，对针对这些现象的研究进行了概述。